The best advice has been said... Throw out nothing.
Or if you do be selective and have good reasoning to do so.
Like it's just too damn big to keep for instance.
I keep everything from computer cases to drink stirrers and more... Model kits are pricier and pricier these days, so buying cheap kits isn't as easy... And buying from HLJ isn't always fun due to international shipping.
Keep your eyes open at toy shows for model kits cheap... Or flea markets or whatnot.
Old Star Wars kits have as useful parts as old battleships... One's no better than the other generally. I just sold the Dagobah Encounter kit I had to Ryan actually and it's almost a full playset unto itself. Little work and it's a fantastic set.